Mn induced modifications of Ga 3d photoemission from (Ga, Mn)As: evidence for long range effects

Using synchrotron based photoemission, we have investigated the Mn-induced changes in Ga 3d core level spectra from as-grown ${\rm Ga}_{1-x}{\rm Mn}_{x}{\rm As}$. Although Mn is located in Ga substitutional sites, and does therefore not have any Ga nearest neighbours, the impact of Mn on the Ga core level spectra is pronounced even at Mn concentrations in the range of 0.5%. The analysis shows that each Mn atom affects a volume corresponding to a sphere with around 1.4 nm diameter.Comment: Submitted to Physical Review B, Brief Repor

Marketing Scottish social enterprises using a label?

Purpose: Social enterprises are competitive businesses in the marketplace, yet insubstantial research has investigated how they market their businesses. This paper aims to investigate the impact a social enterprise label – “Buy the Good Stuff” – used in Edinburgh has had on consumer awareness and explore whether a possible national label could be used as a marketing tool by social enterprises in Scotland. Design/methodology/approach: The study uses a mixed-methods approach, consisting of an online questionnaire with 100 participants and seven semi-structured interviews with representatives of social enterprises involved in the marketing campaign in Edinburgh and representatives of social enterprises who were not involved in the campaign. Findings: Findings indicate that the label used in Edinburgh has had little impact on increasing consumer awareness of social enterprises. However, a national label has the potential to help social enterprises increase consumer awareness. Yet, successful implementation requires thorough design of the label and broad support for its promotion. Practical implications: The paper offers insights into the implementation of a national label. Managers of social enterprises and social enterprise networks should consider the findings when adopting marketing activities. Originality/value: Findings contribute to the sparse literature regarding marketing activities of social enterprises. The paper provides evidence that the broader social enterprise sector and its representatives in Scotland should re-evaluate their position on the introduction of a national label, given that one priority identified for the sector is to create and promote a social enterprise brand which the SE code is not focussed on

Electron correlations in Mnx_xGa1−x_{1-x}As as seen by resonant electron spectroscopy and dynamical mean field theory

After two decades from the discovery of ferromagnetism in Mn-doped GaAs, its origin is still debated, and many doubts are related to the electronic structure. Here we report an experimental and theoretical study of the valence electron spectrum of Mn-doped GaAs. The experimental data are obtained through the differences between off- and on-resonance photo-emission data. The theoretical spectrum is calculated by means of a combination of density-functional theory in the local density approximation and dynamical mean-field theory (LDA+DMFT), using exact diagonalisation as impurity solver. Theory is found to accurately reproduce measured data, and illustrates the importance of correlation effects. Our results demonstrate that the Mn states extend over a broad range of energy, including the top of the valence band, and that no impurity band splits off from the valence band edge, while the induced holes seem located primarily around the Mn impurity.Comment: 5 pages, 4 figure

Ecosystem properties and principles of living systems as foundation for sustainable agriculture – Critical reviews of environmental assessment tools, key findings and questions from a course process

With increasing demands on limited resources worldwide, there is a growing interest in sustainable patterns of utilisation and production. Ecological agriculture is a response to these concerns. To assess progress and compliance, standard and comprehensive measures of resource requirements, impacts and agro-ecological health are needed. Assessment tools should also be rapid, standardized, userfriendly, meaningful to public policy and applicable to management. Fully considering these requirements confounds the development of integrated methods. Currently, there are many methodologies for monitoring performance, each with its own foundations, assumptions, goals, and outcomes, dependent upon agency agenda or academic orientation. Clearly, a concept of sustainability must address biophysical, ecological, economic, and sociocultural foundations. Assessment indicators and criteria, however, are generally limited, lacking integration, and at times in conflict with one another. A result is that certification criteria, indicators, and assessment methods are not based on a consistent, underlying conceptual framework and often lack a management focus. Ecosystem properties and principles of living systems, including self-organisation, renewal, embeddedness, emergence and commensurate response provide foundation for sustainability assessments and may be appropriate focal points for critical thinking in an evaluation of current methods and standards. A systems framework may also help facilitate a comprehensive approach and promote a context for meaningful discourse. Without holistic accounts, sustainable progress remains an illdefined concept and an elusive goal. Our intent, in the work with this report, was to use systems ecology as a pedagogic basis for learning and discussion to: - Articulate general and common characteristics of living systems. - Identify principles, properties and patterns inherent in natural ecosystems. - Use these findings as foci in a dialogue about attributes of sustainability to: a. develop a model for communicating scientific rationale. b. critically evaluate environmental assessment tools for application in land-use. c. propose appropriate criteria for a comprehensive assessment and expanded definition of ecological land use

A Low-Complexity Detector for Memoryless Polarization-Multiplexed Fiber-Optical Channels

A low-complexity detector is introduced for polarization-multiplexed M-ary phase shift keying modulation in a fiber-optical channel impaired by nonlinear phase noise, generalizing a previous result by Lau and Kahn for single-polarization signals. The proposed detector uses phase compensation based on both received signal amplitudes in conjunction with simple straight-line rather than four-dimensional maximum-likelihood decision boundaries.Comment: accepted for publication in IEEE Comm. Let

The contribution of insect prey to the total nitrogen content of sundews (Drosera spp.) determined in situ by stable isotope analysis

The contribution of insect prey to total N in the carnivorous plants, Drosera rotundifolia and D. intermedia, was quantified in situ and without any experimental manipulation using natural abundance stable isotope analysis. Samples of D. rotundifolia and D. intermedia, insects and noncarnivorous reference plants were collected from three contrasting locations across Britain. The proportion of Drosera nitrogen obtained from insect prey was calculated by a mixing model using δ<sup>15</sup>N values from the different plant groups. The mean proportion of Drosera N derived from prey was 50%. There were significant differences in this proportion between sites, and significant differences within sites. There were significant differences between plant tissues and a significant negative relationship between the proportion of N derived from prey and the C : N ratio of Drosera tissues. There was little evidence of differences in prey capture/utilisation in response to N availability, possibly due to a limited range in available N between the sites. However, evidence of a positive benefit of prey capture was apparent through the decrease in C : N ratio with increasing prey N concentrations in the plants

Informal care and the great recession

Macroeconomic downturns can have both an important impact on the availability of informal care and the affordability of formal long-term care. This paper investigates how the demand for and provision of informal care changed during and after the Great Recession in Europe. We use data from the Survey of Health, Aging and Retirement in Europe (SHARE), which includes a rich set of variables covering waves before and after the Great Recession. We find evidence of an increase in the availability of informal care and a reduction in the use of formal health services (doctor visits and hospital stays) after the economic downturn when controlling for year and country fixed effects. This trend is mainly driven by changes in care provision of individuals not cohabiting with the care recipient. We also find a small negative association between old-age health (measured be the number of problems with activities of daily living) and crisis severity. The results are robust to the inclusion of individual characteristics, individual-specific effects and region-specific time trends